I've been arguing this for the past year or so with people who refuse to listen to reason. No overarching story; no need for the threat level to continue to increase from film to film; no need for a trilogy or an overarching linked story. Just an episodic franchise, with a new story with each telling. Just like in the comics.

I think Thanos fits perfectly into this because they could use him as a means to explore the characters. Avengers 1 was the team versus an alien army. Avengers 2 should be the team versus one singular threat. A threat so powerful that it builds and destroys their relationships. Something that can make them have to rethink everything they've every thought before.